Tomic overcame heat stress in 40-degree on-court temperatures to advance to his maiden ATP final with a fighting 7-6 (10-8) 6-4 win over Italian third seed Andreas Seppi.
Victory over the world No.23 was Tomic's seventh straight win of his unbeaten summer and earned the Queenslander a crack at big-serving South African Kevin Anderson in Saturday's twilight final at Olympic Park.
Much is at stake for Tomic.
As well as regaining the national No.1 ranking from Marinko Matosevic, his first-round victim this week, Tomic can join two of the legends of the game in the history books.
If he beats the unseeded Anderson, Tomic will become the first Australian winner in Sydney since Hewitt in 2005 and the first 20-year-old to hoist the trophy since the great Roger Federer in 2002.
"It's about time, I think, I really got to one of these finals," Tomic, a two-time grand slam junior champion, said of his long-awaited breakthrough at senior level.
"To do it here and in Australia is a great privilege and an honour.
"It's going to be a huge final for me and I'm going to give my heart out there to win and I think I can."
Hewitt is a four-time winner of the event and, fittingly, Tomic displayed some of his countryman's trademark fighting spirit to get to the title decider.
After calling for the ATP trainer while leading 5-4 in the opening set, Tomic complained of dizziness and then had to fend off six break points - or mini set points - at 5-all.
At the 6-5 changeover, Tomic sought treatment from the tournament doctor and physio, saying: "Something's wrong, I can't see".
He took two magical pills and then saved four set points in the tiebreaker before snatching the set when Seppi dumped a forehand into the net after 55 minutes.
Seppi, who led Novak Djokovic by two sets to love at last year's French Open, was also the first to falter in the second set.
He dropped serve in the ninth game to give Tomic a 5-4 advantage and the Australian had no trouble closing out the match after one hour, 23 minutes.
Tomic is the first Australian to make the Sydney final since Chris Guccione lost to Dmitry Tursunov in 2008.
Earlier, Anderson denied Frenchman Julien Benneteau in a three-set cliffhanger to make the final.
Anderson saved two match points before prevailing 3-6 6-4 7-6 (10-8) to become the first South African to make the Sydney final in 45 years of open-era tennis.
Tomic beat the 36th-ranked Anderson in their only previous career meeting at ATP level, at the Shanghai Masters in 2011, though the South African defeated the then-teenage Aussie at a Challenger event the year before.
Tomic, ranked 64th after his run of outs last year, is certain to return to the top 50 and will arrive in Melbourne on Monday as the new Australian No.1 if he wins the title.
Tomic launches his Australian Open campaign against Argentine Leonardo Mayer.
If Tomic wins, he is likely to face Slovakian 27th seed Martin Klizan for a fourth career shot at Roger Federer.
And with seven straight wins already this summer, including one over Open titleholder Novak Djokovic, Tomic refuses to believe he can't beat the 17-times grand slam champion.
"That third-round meet is huge but the tennis I've been playing now, if I can win (on Saturday), it's different approaching the Australian Open," Tomic said.
"It's different, especially beating the No.1 in the world last week and coming in so confident. If I can get that one more match under my belt and have eight matches, it's a different feeling. If I get to Roger, it's going to be a interesting match.
"Last I played him was in Cincinnati (last August) where I think he won the tournament. I lost to him in the third round, 6-2 6-4, close match. I think I've improved quite a bit."
Djokovic on Friday said Tomic had all the tools required to "come to the top" - but urged the 20-year-old to maintain his "no fear" attitude in order to fulfil his potential and Australia's hopes of becoming the nation's next tennis superstar.
As question marks remain over his behaviour, Djokovic believes Tomic must keep his steely mindset, then back it up with a commitment to be the best.
"He's still only 19 or 20 years old and he's already played in the quarter-finals of a grand slam and he's showed on several occasions when he plays in the big matches, that he has no fear," Djokovic said.
"He comes in, he knows what his mission is. I believe that's the right mindset. If he's confident at his age right now, it can sound over-confident. But I think he has to keep that kind of mentality.
"He has to believe he can achieve his hopes and his dreams. It has happened for me, so I know how he feels like. If he's committed enough to the sport, with the potential and talent he's got, I'm sure he can come to the top."
The Serbian expects Tomic to make an impact at Melbourne Park over the next fortnight.
"He's been playing great this year. He's showing some maturity on the court which I think is a great change for him," Djokovic said.
"Obviously he's got a lot of expectations because Australia is a country that nurtures a tennis tradition for a long time ... Australia has been producing big legends of the sport like Rod Laver and (Roy) Emerson.
"They're looking for someone who is going to follow up in the new generation. I think Bernard is right up there."